Liquefied petroleum vaporizer with automatic vaporizer bypass

ABSTRACT

A liquid petroleum vaporizer with means to supply vapor from a storage tank under conditions of demand in excess of the capacity of the vaporizer and with an automatically operable valvecontrolled line bypassing the vaporizer when the vapor in the storage tank is adequate to supply the demand.

United States Patent [54] LIQUEFIED PETROLEUM VAPORIZER WITH AUTOMATICVAPORIZER BYPASS 6 Claims 5 Drawing Flgs' ABSTRACT: A liquid petroleumvaporizer with means to US. Cl 62/51, supply vapor from a storage tankunder conditions of demand 62/52 in excess of the capacity of thevaporizer and with an auto- Int. Cl Fl7c 9/02 matically operablevalve-controlled line bypassing the Field of Search 62/51, 50, vaporizerwhen the vapor in the storage tank is adequate to 52 supply the demand.

PRESSURE vAPoI? L NE g @EsPO/VS/ 145' VA L \/E 23 V M 22 7 k 33 38 BACKPRESSURE STORAGE 40 CHECK VAL v5 22 TANK 2 5 41 16 26 k/ stjfftgs FLOW 76A5 REGULATOR T 7 V ,M L/OU/D L nvs VA P OR I 2 ER PrimaryExaminerAlbert W. Davis, Jr. Attorney-Kingsland, Rogers, Ezell, Eilersand Robbins 10 5 THEIEMOSTATIC.

CONTROL. VA LVE LIQUEFIED PETROLEUM VAPORIZER WITH AUTOMATIC VAPORIZERBYPASS BRIEF DESCRIPTION OF THE INVENTION In the system of thisinvention, a vaporizer receives liquid petroleum from a storage tank.The petroleum in the vaporizer is heated to produce vapor and the vaporfrom the vaporizer is delivered to a demand area. The vaporizer has afloat-controlled valve. One of the inputs to the valve is connected by apipe to the upper side of the petroleum tank. The other input to thevalve comes from the vaporizer. When the demand for vapor does notexceed the capacity of the vaporizer to supply vapor, thefloat-controlled valve closes the auxiliary supply line leading from theupper end of the storage tank. When the demand for vapor increases abovethe capacity of the vaporizer to supply vapor, the reduced pressurewithin the vaporizer causes the liquid level therein to rise, raisingthe float and opening the valve to admit auxiliary vapor from thestorage tank. If the demand for vapor is so high that the ability of thevaporizer to supply vapor is exhausted, the float rises still higher andcompletely blocks the supply of vapor from the vaporizer, leaving thevalve open to the pipe supplying vapor from the storage tank. Theforegoing kind of vaporizer system is generally set forth in Mitchell,et al. US. Pat. No. 2,551,501.

This invention adds a bypass pipe leading directly from the storage tankto the demand area. A pressure compensating valve operates in responseto pressure within the storage tank to control the flow of vapor throughthe bypass line. The pressure compensating valve is set to cause vaporfrom the storage tank to bypass the vaporizer and flow directly to thedemand area when the pressure compensating valve senses that thecorresponding storage tank pressure is at or above a predetermined valuebecause, at sufficiently high ambient temperatures and/or sufficientlylow demand, the petroleum within the storage tank will boil and generateenough vapor to supply the demand. When the demand for vapor increasesor the ambient temperature drops below a level at which the petroleum inthe storage tank will boil at a sufficient rate to supply enough vapor,the pressure compensating valve senses the corresponding reducedpressure and blocks the flow of vapor through the line bypassing thevaporizer. With the bypass line blocked, vapor within the capacity ofthe vaporizer is supplied to the demand area and, if the demand forvapor exceeds the capacity of the vaporizer to supply vapor, the surplusflow valve opens to permit auxiliary vapor to be supplied from thestorage tank.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of thecontrol system.

FIG. 2 is an enlarged elevation view in vertical section through thevaporizer.

FIG. 3 is a further enlarged view in vertical section of the surplusflow valve.

FIG. 4 is a view in section taken along the line 4-4 of FIG. 3.

FIG. 5 is a schematic diagram of a modification of the control system.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, the controlsystem includes a large petroleum tank 11 and a vaporizer 12. A pipe 13is connected from the lower side of the storage tank 11 through the wall14 of the vaporizer 12 to deliver liquid petroleum into the lower end ofthe vaporizer 12. There is a shutoff valve 15 in the pipe 13. Althoughnot shown, the vaporizer 12 also has the conventional burner and pilotthat use vapor from the storage tank 11 as fuel, with the burner beingcontrolled by a thermostat, all as conventional in the art.

As described in the aforesaid Mitchell, et al. patent, a surplus flowvalve 16 is mounted at the upper end of the vaporizer 12. The surplusflow valve 16 has a valve housing 17. As shown in FIG. 3, one inletpassage 18 in the valve housing 17 leads from the vaporizer 12 to avalve seat 19. Another inlet passage 20 leads to another valve seat 21spaced from the valve seat 19. A suitable pipe 22 connects the inletpassage 20 to the upper end of the storage tank 11. There is a manuallycontrolled shutoff valve 23 in the pipe 22. An outlet passage 24 islocated between the valve seats 19 and 21. A pipe 25 leads from theoutlet passage 24 through a gas pressure regulator 26 to the demand areawhich comprises appliances and the like.

A float 28 is positioned within the housing 14 of the vaporizer 12. Thefloat 28 is guided for vertical movement by a vertical pin 29 that canreciprocate within an opening 30 in a guide 31 welded to the bottominner surface of the housing 14. A rod 32 extends upwardly from the topof the float. A valve member 33 is mounted on the rod 32 for movementtoward and away from the valve seat 19. Another valve member 34 ismounted on the upper end of a thin rod 35 that extends upwardly from thecenter of the valve member 33. As the rod 32 moves up and down, thevalve member 34 moves away from and toward the valve seat 21 and thevalve member 33 moves toward and away from the valve seat 19. There aregrooves 36 in the sidewall of the inlet passage 20 to assure the freeflow of vapor past the valve member 34 when the valve member 34 is abovethe valve seat 21.

For the control system of this invention, a pipe 38 is connected betweenthe pipe 22 that leads from the upper end of the storage tank 11 and thepipe 25 that leads from the outlet chamber 24 of the surplus flow valve16. A pressure responsive control valve 39 is mounted in the pipe 38.The pressure responsive control valve 39 is of a conventional design andis connected to operate in response to vapor pressure in the upper endof the storage tank 11. The valve 39 is set to remain closed so long asthe vapor within the storage tank 11 is below a predetermined value andto open when the vapor pressure within the storage tank 11 reaches orexceeds the predetermined value. For example, when the petroleum in thestorage tank 11 is propane, the pressure responsive control valve 39 maybe set to open when it senses a pressure within the storage tank of 20p.s.i.g. or higher. A manual shutoff valve 40 is mounted in the pipe 38downstream of the pressure responsive control valve 39.

A back pressure check valve 41 is mounted in the pipe 25 between thesurplus flow valve 16 and the juncture between the pipe 25 and the pipe38. The back pressure check valve 4-1 is of a conventional design of thetype that produces a pressure drop, preferably of about 3 p.s.i., invapor flowing through the valve 41. When the vapor from the storage tank11 has this free path through the bypass pipe 38 to the demand area, thepressure within the vaporizer 12 can build up to such an extent that allthe liquid is forced from the vaporizer 12 back to the storage tank 11,deactivating the vaporizer 12 in the usual manner, such as by athermostatic control value 50 that temporarily turns off the burner 51.The back pressure check valve 41 in the pipe 25 downstream of thesurplus flow valve 16 assures that, as long as vapor can flow throughthe pipe 38, a back pressure will be maintained to impede the flow ofvapor from the vaporizer and permit the pressure in the vaporizer tobuild up and produce a shutting off of the vaporizer.

A modified control system 45 is shown in FIG. 5. In this modifiedcontrol system 45, most of the components and connections are the sameas described for the control system 10 shown in FIG. 1, and for theseidentical components and connections, identical reference charactershave been used. In this modified control system, a pressure responsivecontrol valve 46 is connected in the pipe 25 between the surplus flowvalve 16 and the juncture between the pipe 25 and the pipe 38. Thepressure responsive control valve 46 is also connected to respond tovapor pressure within the storage tank 11. However, as distinguishedfrom the pressure responsive control valve 39 of the system shown inFIG. I, the pressure responsive control valve 46 is designed to closewhen the pressure of vapor within the storage tank 11 reaches or exceedsa predetermined value and to open when the pressure of vapor within thestorage tank 11 drops below the predetermined value. Again, if thepetroleum within the storage tank is vapor, the pressure responsivecontrol valve 46 may be set to close at a sensed pressure of 20 p.s.i.g.

A back pressure check valve 47 is connected in the pipe 38. The backpressure check valve 47 is of a conventional design that imparts apressure drop of about 3 psi. to vapor flowing through it.

OPERATION The control system can be made operable by opening themanually controlled shutoff valves 15, 23 and 40. Assuming the vaporpressure within the tank 11 is below 20 p.s.i.g. and the pressureresponsive control valve 39 of FIG. 1 is therefore closed, thethermostat will cause the vaporizer burner (not shown) to burn to boilliquid within the vaporizer 12. With low pressure in the vaporizer l2,liquid petroleum can flow from v from rising above a normal level.Hence, the float 28 will remain in a normal suspended position thatholds the valve member 33 below the valve seat 19 and holds the valvemember 34 in contact with the valve seat 21. Since the valve member 34is in contact with the valve seat 21, no vapor can flow from the pipe 22past the valve seat 21. Vapor is supplied from the vaporizer 12 byflowing through the inlet passage 18 in the surplus flow valve 16, pastthe valve seat 19, through the outlet passage 24, the pipe 25,, the backpressure check valve 41, and the gas pressure regulator 26, on to thedemand area.

If the demand for vapor is reduced, so that vapor is produced in thevaporizer 12 at a greater rate than is being drawn off by the demandarea, the vapor pressure within the vaporizer housing 14 will rise. Thisrise in vapor pressure will force the liquid level within the vaporizer12 down, returning some liquid petroleum to the storage tank 11. Thisreduces the amount of liquid in the hot areas of the vaporizer housing14 and reduces the rate of boiling of the petroleum and therefore therate of production of the vapor. In this manner, the vaporizer 12 tendsto produce vapor at a rate corresponding with the rate of demand forvapor.

If the rate of vapor delivered to the demand area increases because ofincreasing demand for vapor, a greater rate of vapor will be withdrawnfrom the vaporizer housing 14, reducing the pressure of vapor within thevaporizer housing 14. This permits more liquid petroleum to flow fromthe storage tank 11 into the vaporizer 12, resulting in raising thelevel of liquid within the vaporizer 12 and increasing the amount ofliquid in the hot area of the vaporizer housing 14. The result is anincrease in the rate of boiling of the petroleum to respond to thegreater demand rate for vapor.

During the normal variations in liquid level within the vaporizer 12,the float 28 simply hangs from the stem 32 as the valve member 34 isseated against the valve seat 21. Therefore, for normal variations invapor demand within the capacity of the vaporizer 12 to supply vapor tomeet that demand, no flow of vapor can take place past the valve seat21. However, if the demand for vapor exceeds the capacity of thevaporizer to generate vapor, the pressure of the vapor within thevaporizer housing 14 will continue to fall until the level of liquidwithin the vaporizer rises to raise the float 28 and lift the valvemember 34 from the valve seat 21. This permits auxiliary vapor to flowfrom the upper end of the storage tank 11 past the valve seat 21 to theoutlet passage 24 for mixture with vapor being supplied from thevaporizer 12. If the demand for vapor becomes very high, the liquidlevel within the vaporizer housing 14 will rise still further until thevalve member 33 seats against the valve seat 19, completely blocking theflow of vapor from the vaporizer 12. Then, all the vapor is suppliedfrom the storage tank 11. Of course, as soon as the valve member 33seats against the valve seat 19, the vaporizer 12 can rapidly build upvapor within the vaporizer housing 14, reestablishing the ability of thevaporizer 12 to supply vapor. Hence, the increased pressure within thevaporizer 12 will again force liquid from the vaporizer, lowering thefloat 28, and dropping the valve member 33 from the valve seat 19.

The foregoing operation can take place so long as the pressureresponsive control valve 39 is closed. However, on warm days when thepetroleum within the storage tank 11 boils more readily and creates morevapor, thereby increasingthe pressure within the storage tank 11, orduring times of relatively low demand for vapor by the demand area sothat the rate of withdrawal of vapor is quite low and the storage tank11 can maintain a relatively high pressure, the valve 39 may open. Thevalve 39 is set to respond to the pressure variations within the storagetank 11 and to open whenever the pressure within the tank 11 reaches orexceeds the set pressure for the valve 39. If the valve 39 is set toopen upon sensing a pressure of 20 p.s.i.g., for example, and if thepressure within the storage tank 11 reaches or exceeds 20 p.s.i.g., thevalve 39 will permit vapor to flow directly from the storage tank 11through the pipe 22, to the pipe 38, and through the now open pressureresponsive control valve 39 to the pipe 25, through the gas pressureregulator 26, and on to the demand area.

If the demand for vapor increases, or if the temperature drops so thatless boiling of petroleum in the storage tank 11 occurs, or if any otherfactor occurs which reduces the vapor pressure within the storage tank11 to a value below 20 p.s.i.g., the pressure responsive control valve39 closes. This blocks further flow of vapor from the storage tank 11through the bypass pipe 38 and reestablishes the functions andoperations of the vaporizer 12 to supply vapor, perhaps with auxiliaryvapor to be supplied from the upper end of the storage tank 11, all asalready described. Thus, the provision of the bypass pipe 38, thepressure responsive control valve 39 and the back pressure check valve41, permit the supplying of vapor directly from the storage tank 11 whenconditions so permit, resulting in a saving of such loss of petroleum asis required for operation of the vaporizer 12. Under conditions when thestorage tank 11 cannot supply the demands of the demand area, such aswhen the ambient temperature will not boil the petroleum within thestorage tank 11 rapidly enough, or when the demand for vapor increases,the pressure responsive valve 39 automatically closes and the vaporizer12 is automatically activated to produce vapor.

In the modification of FIG. 5, the operation of the vaporizer 12 inconjunction with the storage tank 11 is as described in connection withthe control system 10 of FIG. 1. The operation of the remainder of thesystem 45 is similar to that of the system 10 except that, since thepressure responsive control valve 46 is in the pipe 25 on the outletside of the surplus flow valve 16, the valve 46 closes rather than openswhen the pres sure within the storage tank 11 reaches this set value forthe valve 46, such as 20 p.s.i.g. When the valve 46 closes, no vapor canflow from the vaporizer 12. Hence, vapor can flow from the storage tank11 through the pipe 22, the pipe 38, the back pressure check valve 47,and the gas pressure regulator 26, to the demand area. When the pressurewithin the storage tank 11 drops to a value below 20 p.s.i.g., thepressure responsive control valve 46 senses the drop in pressure andopens, opening the pipe 25 leading from the surplus flow valve 16. Now,vapor can flow from the vaporizer 12 through the pipe 25 and the valve46 to the demand area. When vapor can flow through the valve 46, all thevapor demanded by the demand area will be supplied from the surplus flowvalve 16 because the back pressure check valve 47 creates a pressuredrop of about 3 psi. and impedes tlow through the pipe 38. This vaporwill be supplied either from the vaporizer 12, the vaporizer 12 withauxiliary vapor from the storage tank 11, or

from the storage tank 11 alone, depending upon the demand for vapor andthe consequent setting of the surplus flow valve 16.

Various changes and modifications may be made within the scope of thisinvention as will be readily apparent to those skilled in the art. Suchchanges and modifications are within the scope and teaching of thisinvention is defined by the claims appended hereto.

lclaim:

l. A system for supplying vapor to a demand'area comprising a storagetank for containing liquid petroleum, a vaporizer,

means to deliver liquid from the storage tank to the vaporizer, means toboil liquid in the vaporizer to produce vapor, means to supply vaporfrom the vaporizer to the demand area, means bypassing the vaporizer forsupplying vapor from the storage tank to the demand area, pressureresponsive valve means in the bypass vapor supply means, the pressureresponsive valve means being normally closed and being adapted to openin response to increases in pressure within the storage tank to or abovea predetermined valve for alternately blocking and unblocking the flowof vapor through the bypass supply means, and a back pressure checkvalve on the outlet side of the vaporizer for creating a pressure dropbetween the inlet and the outlet of the back pressure check valve toassure deactivation of the vaporizer when the pressure responsivecontrol valve means is open, and means responsive to a condition withinthe vaporizer to cut off the flow of heat to and to deactivate thevaporizer.

2. The vaporizer system of claim 1 including a surplus flow valve, afirst inlet passage to the surplus flow valve, means connecting thefirst inlet passage to the vaporizer for delivering vapor from thevaporizer to the first inlet passage, a second inlet passage to thesurplus flow valve, means connecting the upper end of the storage tankto the second inlet passage for delivering vapor from the storage tankto the second inlet passage, an outlet passage from the surplus flowvalve, means connecting the outlet passage for delivering vapor to thedemand area, a normally closed valve for blocking the second inletpassage and a normally open valve movable to block the first inletpassage, and means to unblock the second inlet passage when the demandfor vapor increases above the capacity of the vaporizer to supply vapor.

3. The vaporizer system of claim 2 including means to close the firstpassage when the demand for vapor reaches such a high level that thevaporizer becomes exhausted of vapor.

4, A system for supplying vapor to a demand area comprising a storagetank for containing liquid petroleum, a vaporizer, a pipe for deliveringliquid petroleum from the storage tank to the vaporizer and, under theinfluence of liquid pressure in the storage tank and vapor pressure inthe vaporizer, for maintaining liquid in the vaporizer in properquantity to supply the rate of vaporization in the vaporizer undernormal operating conditions, a surplus flow valve. having an outletcommunicating with the demand area and having a first inletcommunicating with the vapor area within the vaporizer and a secondinlet communicating with the vapor area within the storage tank,normally closed valve means for normally blocking the second inlet andnormally open valve means for normally opening the first inlet under thesaid normal operating conditions, the normally closed valve means beingoperable in response to increases in demand for vapor above the capacityof the vaporizer to supply vapor, the normally open valve means beingcloseable in response to substantial filling of the vaporizer withliquid, a pipe bypassing the vaporizer and connected directly betweenthe vapor area of the storage tank and the demand area, a normallyclosed pressure responsive valve in the bypassing pipe openable inresponse to increase in pressure within the storage tank to or above apredetermined value, and a back pressure check valve for creating apressure drop between the vaporizer and the demand area therebyproviding a greater impedance to the flow of vapor from the vaporizerthan through the bypassing pipe and means responsive to a conditionwithin the vaporizer to cut off the flow of heat to and to deactivatethe vaporizer.

5. The system of claim 4 wherein the bypassing check valve produces apressure drop of about 3 p.s.i.

6. The system of claim 4 wherein the pressure responsive valve is set toopen upon sensing a pressure of about 20 p.s.i. within the storage tank.

2. The vaporizer system of claim 1 including a surplus flow valve, afirst inlet passage to the surplus flow valve, means connecting thefirst inlet passage to the vaporizer for delivering vapor from thevaporizer to the first inlet passage, a second inlet passage to thesurplus flow valve, means connecting the upper end of the storage tankto the second inlet passage for delivering vapor from the storage tankto the second inlet passage, an outlet passage from the surplus flowvalve, means connecting the outlet passage for delivering vapor to thedemand area, a normally closed valve for blocking the second inletpassage and a normally open valve movable to block the first inletpassage, and means to unblock the second inlet passage when the demandfor vapor increases above the capacity of the vaporizer to supply vapor.3. The vaporizeR system of claim 2 including means to close the firstpassage when the demand for vapor reaches such a high level that thevaporizer becomes exhausted of vapor.
 4. A system for supplying vapor toa demand area comprising a storage tank for containing liquid petroleum,a vaporizer, a pipe for delivering liquid petroleum from the storagetank to the vaporizer and, under the influence of liquid pressure in thestorage tank and vapor pressure in the vaporizer, for maintaining liquidin the vaporizer in proper quantity to supply the rate of vaporizationin the vaporizer under normal operating conditions, a surplus flow valvehaving an outlet communicating with the demand area and having a firstinlet communicating with the vapor area within the vaporizer and asecond inlet communicating with the vapor area within the storage tank,normally closed valve means for normally blocking the second inlet andnormally open valve means for normally opening the first inlet under thesaid normal operating conditions, the normally closed valve means beingoperable in response to increases in demand for vapor above the capacityof the vaporizer to supply vapor, the normally open valve means beingcloseable in response to substantial filling of the vaporizer withliquid, a pipe bypassing the vaporizer and connected directly betweenthe vapor area of the storage tank and the demand area, a normallyclosed pressure responsive valve in the bypassing pipe openable inresponse to increase in pressure within the storage tank to or above apredetermined value, and a back pressure check valve for creating apressure drop between the vaporizer and the demand area therebyproviding a greater impedance to the flow of vapor from the vaporizerthan through the bypassing pipe and means responsive to a conditionwithin the vaporizer to cut off the flow of heat to and to deactivatethe vaporizer.
 5. The system of claim 4 wherein the bypassing checkvalve produces a pressure drop of about 3 p.s.i.
 6. The system of claim4 wherein the pressure responsive valve is set to open upon sensing apressure of about 20 p.s.i. within the storage tank.